Ammonia pollution could be biggest threat to Delta smelt

Maybe it's not the giant pumps at Tracy that send Delta water to the southlands that are killing the Delta smelt.

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By The Record

recordnet.com

By The Record

Posted Jun. 11, 2008 at 12:01 AM

By The Record

Posted Jun. 11, 2008 at 12:01 AM

» Social News

Maybe it's not the giant pumps at Tracy that send Delta water to the southlands that are killing the Delta smelt.

Maybe it's toxic levels of ammonia released from upstream wastewater treatment plants, according to two recent studies. If that's the case, look for more expense as those plants are upgraded.

Ammonia, a common byproduct of human urine and feces, is entering the labyrinth of waterways that make up the estuary from one primary source: Sacramento.

That city's regional sewage treatment plant is the largest single source of ammonia in the Delta. It discharges treated wastewater from nearly 1.4 million people into the Sacramento River near Freeport without removing ammonia.

In fact, the ammonia load in Sacramento's wastewater has more than doubled since 1985 due to rapid urbanization and is now more than 125,000 gallons per month. That's 10 times more than the Stockton sewage plant.

Ammonia is the primary culprit in fish kills. A report released last fall based on data from the Environmental Protection Agency alleged Stockton violated its wastewater discharge permit 50 times in 2005, with ammonia levels exceeding its permit by anywhere from 23 percent to 1,245 percent.

Stockton officials disputed the figures when they were released but point out that a $42 million upgrade to the plant, including equipment that uses bacteria to eat ammonia before it is discharged into the river, has alleviated the problem.

Not so in Sacramento.

Officials there contend it could cost as much as $1 billion - and triple monthly sewer bills to residents throughout the region - to upgrade their plant to remove ammonia.

"We are a very large discharger," said Mary Snyder, a Sacramento district engineer. "But when you look at the Sacramento River, we have a small impact on the river."

True, the enormous flow of that river probably has diluted toxins dumped there in years past, but they're still toxins. (We also used to discharge raw sewage into our waterways, where it was "diluted" before flowing to the next community downstream.) But with urban growth and growing discharge levels, that free dilution solution might not work anymore.

Clearly, we shouldn't jump to conclusions. In fact, San Francisco State University scientists whose studies showed how ammonia was disrupting the food chain in the Delta caution against moving too quickly.

"We're not going out on the edge to say this is the whole answer," San Francisco State oceanographer Richard Dugdale said. "But we think it's part of the reason for the decline in the (ecological) productivity."

In other words, let's get back out there and find out what's gone wrong. And if necessary, fix it before it gets any worse.